Methods and apparatuses for treating a hydrocarbon-containing feed stream

ABSTRACT

Embodiments of methods and apparatuses for treating a hydrocarbon-containing feed stream are provided. The method comprises the steps of contacting the hydrocarbon-containing feed stream comprising C 4 , C 5 , C 6 , and/or C 7  hydrocarbons, water, and contaminants with a Linde Type A molecular sieve at dehydration conditions effective to remove water and form a dehydrated feed stream. The contaminants comprise oxygenates, sulfur compounds, or combinations thereof. The dehydrated feed stream is contacted with a sodium faujasite molecular sieve having a silica/alumina molar ratio of from about 2 to about 2.5 at absorption conditions effective to remove the contaminants and form a dehydrated contaminant-depleted feed stream.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Division of copending application Ser. No.13/284,512 filed Oct. 28, 2011, the contents of which are herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to methods and apparatuses fortreating a hydrocarbon-containing feed stream, and more particularlyrelates to methods and apparatuses for treating a hydrocarbon-containingfeed stream including removing water and other contaminants, such asoxygenates and/or sulfur compounds, from the feed stream.

BACKGROUND

The removal of water and other contaminants, such as oxygenates and/orsulfur compounds, from light hydrocarbons is often performed to producea clean hydrocarbon product. The clean hydrocarbon product can befurther treated using catalytic reactions, such as catalyticisomerization, to produce other hydrocarbons, increase octane, improvethe product value, and/or the like. In particular, catalysts that aretypically used for catalytic isomerization and other catalytic reactionsare very sensitive to water, oxygenates, and sulfur compounds, which cancause deactivation of the catalyst, thereby reducing catalyst life,increasing the number of catalyst regenerations, and/or requiringcomplete replacement of the catalyst.

One conventional process for removing water and other contaminants fromlight hydrocarbons employs a bed arrangement that contains a relativelylarge pore molecular sieve as an absorbent material. A light hydrocarbonstream is passed through the bed arrangement and the molecular sieveabsorbs much of the water and other contaminants from the stream toproduce a clean hydrocarbon product. As the molecular sieve removes theundesirable components from the stream, its surface and pores becomesaturated with water and to a lesser extent the other contaminants,causing the molecular sieve to become less active. To restore itsactivity, the molecular sieve is regenerated at higher temperatures tohelp remove the absorbed water and other contaminants. Although water isreadily removed from the molecular sieve during regeneration, the othercontaminants tend to remain and react at the higher temperatures to forma gummy residue. The gummy residue steadily builds up during eachadditional regeneration, plugging the pores and causing prematurepermanent deactivation of the molecular sieve. Since regeneration atthis point is no longer effective to restore activity, the molecularsieve needs to be replaced, which is expensive and time consuming.

Accordingly, it is desirable to provide methods and apparatuses fortreating a hydrocarbon-containing feed stream using an absorbentmaterial(s) to remove water and other contaminants to produce a cleanhydrocarbon product without causing premature permanent deactivation ofthe absorbent material(s). Moreover, it is desirable to provide methodsand apparatuses for treating a hydrocarbon-containing feed stream toproduce a clean hydrocarbon product using an absorbent material(s) thatmay be frequently regenerated to restore activity without causing asteady buildup of gummy residue on the absorbent material(s).Furthermore, other desirable features and characteristics of the presentinvention will become apparent from the subsequent detailed descriptionand the appended claims, taken in conjunction with the accompanyingdrawings and this background.

BRIEF SUMMARY

Methods and apparatuses for treating a hydrocarbon-containing feedstream are provided herein. In accordance with an exemplary embodiment,a method for treating a hydrocarbon-containing feed stream comprises thesteps of contacting the hydrocarbon-containing feed stream comprisingC₄, C₅, C₆, and/or C₇ hydrocarbons, water, and contaminants with a LindeType A molecular sieve at dehydration conditions effective to removewater and form a dehydrated feed stream. The contaminants compriseoxygenates, sulfur compounds, or combinations thereof. The dehydratedfeed stream is contacted with a sodium faujasite molecular sieve havinga silica/alumina molar ratio of from about 2 to about 2.5 at absorptionconditions effective to remove the contaminants and form a dehydratedcontaminant-depleted feed stream.

In accordance with another exemplary embodiment, a method for treating ahydrocarbon-containing feed stream is provided. The method comprises thesteps of introducing the hydrocarbon-containing feed stream comprisingC₄, C₅, C₆, and/or C₇ hydrocarbons, water, and contaminants to aregenerative dehydration zone that comprises a Linde Type A molecularsieve at dehydration conditions effective to remove water and form adehydrated feed stream and a spent Linde Type A molecular sieve. Thecontaminants comprise oxygenates, sulfur compounds, or combinationsthereof. The spent Linde Type A molecular sieve is regenerated in theregenerative dehydration zone at regenerative conditions effective toform a regenerated Linde Type A molecular sieve. At least a portion ofthe dehydrated feed stream is introduced to a guard bed that containssodium faujasite molecular sieve having a silica/alumina molar ratio offrom about 2 to about 2.5 and that is operating at absorption conditionseffective to remove the contaminants and form a dehydratedcontaminant-depleted feed stream.

In accordance with another exemplary embodiment, an apparatus fortreating a hydrocarbon-containing feed stream is provided. The apparatuscomprises a first dryer containing a first quantity of Linde Type Amolecular sieve. The first dryer is configured to receive thehydrocarbon-containing feed stream comprising C₄, C₅, C₆, and/or C₇hydrocarbons, water, and contaminants and to operate in a firstdehydration mode at dehydration conditions effective to remove water andform a dehydrated feed stream and a first quantity of spent Linde Type Amolecular sieve. The contaminants comprise oxygenates, sulfur compounds,or combinations thereof. A guard bed contains sodium faujasite molecularsieve having a silica/alumina molar ratio of from about 2 to about 2.5and is configured to receive at least a portion of the dehydrated feedstream and to operate at absorption conditions effective to remove thecontaminants and form a dehydrated contaminant-depleted feed stream.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and wherein:

FIG. 1 schematically illustrates an apparatus for treating ahydrocarbon-containing feed stream in accordance with an exemplaryembodiment; and

FIG. 2 schematically illustrates a regenerative dehydration zone fortreating a hydrocarbon-containing feed stream in accordance with anexemplary embodiment.

DETAILED DESCRIPTION

The following Detailed Description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Furthermore, there is no intention to be bound by any theorypresented in the preceding background or the following detaileddescription.

Various embodiments contemplated herein relate to methods andapparatuses for treating a hydrocarbon-containing feed stream. Unlikethe prior art, the exemplary embodiments taught herein includecontacting a hydrocarbon-containing feed stream comprising C₄, C₅, C₆,and/or C₇ hydrocarbons, water, and contaminants, such as oxygenatesand/or sulfur compounds, with a Linde Type A molecular sieve, such as,for example, a Linde Type A molecular sieve, at dehydration conditionseffective to selectively remove water from the feed stream preferablywithout removing the contaminants to form a dehydrated feed stream. Asused herein, C_(x) means hydrocarbon molecules that have “X” number ofcarbon atoms. As will be discussed in further detail below, the LindeType A molecular sieve is a porous zeolitic molecular sieve that has arelatively small pore size. The inventors have found that the relativelysmall pore size of the Linde Type A molecular sieve promotes selectivelyabsorbing water from the feed stream by allowing the smaller watermolecules to readily enter into the small pores while the largercontaminant molecules, e.g., oxygenate and/or sulfur compound molecules,are effectively blocked from entering the small pores. Therefore, as theLinde Type A molecular sieve loses its activity and becomes spent, thesurface and pores of the spent Linde Type A molecular sieve aresaturated with water but remain substantially free of the contaminants.

In an exemplary embodiment, the spent Linde Type A molecular sieve isregenerated to restore its activity. The spent Linde Type A molecularsieve is regenerated at regenerative conditions that include arelatively high temperature to help drive off the absorbed water andform a regenerated Linde Type A molecular sieve. Since the spent LindeType A molecular sieve is substantially free of the contaminants, agummy residue is preferably not formed on the molecular sieve fromexposure to the higher temperatures during regeneration. Therefore, theLinde Type A molecular sieve can be regenerated frequently as requiredrestoring its activity without forming a buildup of gummy residue thatmay otherwise cause premature permanent deactivation of the molecularsieve.

The dehydrated feed stream is then contacted with sodium faujasitemolecular sieve having a silica/alumina molar ratio of from about 2 toabout 2.5, such as, for example, 13×molecular sieve, at absorptionconditions effective to remove the contaminants and form a dehydratedcontaminant-depleted feed stream. As will be discussed in further detailbelow, the sodium faujasite molecular sieve having a silica/aluminamolar ratio of from about 2 to about 2.5 is a porous zeolitic molecularsieve having a relatively large pore size of up to about 10 Å, forexample. The relatively large pore size of the sodium faujasitemolecular sieve promotes absorption of the contaminants from thedehydrated feed stream by allowing the larger contaminant molecules toreadily enter into the large pores. Because the dehydrated feed streamis substantially free of water, the surface and pores of the sodiumfaujasite molecular sieve remain substantially free of water, which theinventors have found prolongs the activity of the molecular sieve.Preferably, the sodium faujasite molecular sieve is not regenerated andtherefore, a gummy residue that may otherwise be formed from exposingthe contaminants to higher temperatures during regeneration is notproduced.

In an exemplary embodiment, the dehydrated contaminant-depleted feedstream is a clean hydrocarbon product that is suitable for furthertreatment using a catalytic reaction. In one specific example of thisembodiment, the dehydrated contaminant-depleted feed stream is contactedwith an isomerization catalyst in the presence of hydrogen atisomerization conditions effective to form an isomerization effluent.The isomerization effluent comprises branched paraffins, normalparaffins, and naphthenes.

Referring to FIG. 1, a schematic depiction of an apparatus 10 fortreating hydrocarbons in accordance with an exemplary embodiment isprovided. As illustrated, the apparatus 10 comprises a regenerativedehydration zone 12 that is in fluid communication with a guard bed 14and a paraffin isomerization zone 16 that is in fluid communication withthe guard bed 14. A hydrocarbon-containing feed stream 18 is introducedto the regenerative dehydration zone 12. The hydrocarbon-containing feedstream 18 comprises C₄, C₅, C₆, and/or C₇ hydrocarbons, water, andcontaminants. Some examples of C₄, C₅, C₆, and/or C₇ hydrocarbonsinclude, but are not limited to, paraffins, olefins, naphthenes, and/oraromatics. Some examples of contaminants include, but are not limitedto, oxygenates such as carbon dioxide, ethanol, methanol, tertiary butylalcohol, dimethyl ether, methyl tertiary butyl ether, and the like; andsulfur compounds such as hydrogen sulfide, mercaptans, carbonyl sulfide,and the like. In one example, the hydrocarbon-containing feed stream 18is formed upstream at least in part by a raffinate stream from anaromatics extraction unit. The raffinate stream is highly paraffinic andcontains trace amounts of sulfolane, which is an extraction solvent usedin the aromatics extraction unit. Sulfolane is a contaminant that isboth an oxygenate and a sulfur compound, and is particularly poisonousto many isomerization catalysts that may be used downstream in theparaffin isomerization zone 16, as will be discussed in further detailbelow. In an exemplary embodiment, sulfolane is present in thehydrocarbon-containing feed stream 18 in an amount of about 1 weightpart per million (wt. ppm) or greater.

The regenerative dehydration zone 12 comprises a first dryer 20 and asecond dryer 22 that are in fluid communication with each other. Each ofthe dryers contains Linde Type A molecular sieve, such as Linde 3Amolecular sieve. As used herein, the term “molecular sieve” is definedas a class of adsorptive desiccants that are highly crystalline innature, distinct from amorphous materials such as gamma-alumina. As usedherein, the terms “absorb,” “absorbed,” “absorbing,” “absorptive,” and“absorption” are used broadly and are to be understood to also include“adsorb,” “adsorbed,” “adsorbing,” “adsorptive,” and/or “adsorption.”Various types of molecular sieves include aluminosilicate materialscommonly known as zeolites. As used herein, the term “zeolite” ingeneral refers to a group of naturally occurring and synthetic hydratedmetal aluminosilicates, many of which are crystalline in structure.There are, however, significant differences between the varioussynthetic and natural materials, such as differences in chemicalcomposition, crystal structure and physical properties. The zeolitesoccur as agglomerates of fine crystals or are synthesized as finepowders and are preferably tableted or pelletized for large-scaleadsorption uses. Zeolites are characterized by having pore openings ofuniform dimensions in which the pore size may be varied by employingdifferent metal cations using ion exchange as is well known in the art.As used herein, “pore size” is defined as the free diameter of theappropriate silicate ring in the zeolite structure. A Linde Type Amolecular sieve (e.g. Linde 3A molecular sieve) is a porous zeoliticmaterial having a Linde Type A structure and is described in The Atlasof Zeolite Structure Types by W. M. Meier. In the case of Linde 3Amolecular sieve, the Linde Type A material has been potassium ionexchanged to reduce the pore size to about 3 to about 3.5 Å. Inparticular, Linde Type A molecular sieve is built by linking sodalitecages through double four-rings to create a cavity accessible tomolecules no larger than water via a three-dimensional eight-ringchannel system.

As illustrated, the regenerative dehydration zone 12 is configured for“closed loop product regeneration.” The first and second dryers 20 and22 are configured as a swing bed arrangement 24 in which one of thefirst and second dryers 20 and 22 is in a dehydration mode 26 and theother of the first and second dryers 20 and 22 is in a regenerative mode28. In particular, when a first plurality of valves 31 are in an openedposition and a second plurality of valves 32 are in a closed position,the first dryer 20 is in the dehydration mode 26 and the second dryer 22is in the regenerative mode 28. Alternatively, when the first pluralityof valves 31 are in the closed position and the second plurality ofvalves 32 are in the opened position, the first dryer 20 is in theregenerative mode 28 and the second dryer 22 is in the dehydration mode26.

As illustrated, the first dryer 20 in the dehydration mode 26 receivesthe hydrocarbon-containing feed stream 18 and is operating atdehydration conditions. In an exemplary embodiment, the dehydrationconditions include a temperature of from about 0 to about 60° C.,preferably of about 0 to about 50° C., and more preferably of aboutambient, and a pressure so as to maintain a liquid phase, such as, forexample, of from about 350 to about 4200 kPa. The hydrocarbon-containingfeed stream 18 contacts the Linde Type A molecular sieve and water isselectively absorbed into the molecular sieve to form a dehydrated feedstream 30. As the surface and pores of the Linde Type A molecular sievebecome saturated with water, the molecular sieve loses activity andforms spent Linde Type A molecular sieve. Preferably, the dehydratedfeed stream 30 comprises water that is present in an amount of about 1wt. ppm or less, and the contaminants remain present at about the samelevel as in the hydrocarbon-containing feed stream 18. As such, thespent Linde Type A molecular sieve is primarily saturated with water andremains substantially free of the contaminants.

In the regenerative mode 28, the second dryer 22, which was previouslyin the dehydration mode 26 as discussed in the foregoing paragraph withrespect to the first dryer 20, contains spent Linde Type A molecularsieve. A portion 34 of the dehydrated feed stream 30 is passed through aheater 36 and is heated to a temperature preferably of from about 200 toabout 320° C. to form a heated product regeneration stream 38. In anexemplary embodiment, the heated product regeneration stream 38 isintroduced to the second dryer 22 that is operating at regenerativeconditions including a temperature of from about 200 to about 320° C.The heated product regeneration stream 38 contacts the spent Linde TypeA molecular sieve and removes water to restore activity to the molecularsieve, forming regenerated Linde Type A molecular sieve and a spentproduct regeneration stream 40. The spent product regeneration stream 40is passed through a cooler 42 where it is cooled to a temperature ofabout 60° C. or less and is introduced to a separation unit 44. Theseparation unit 44 separates water from the spent product regenerationstream 40, forming a water waste stream 45 and a hydrocarbon-containingstream 46 that is combined with the hydrocarbon-containing feed stream18.

In an alternative embodiment and as illustrated in FIG. 2, theregenerative dehydration zone 12 is configured for “open loopregeneration.” In particular, the first and second dryers 20 and 22 areconfigured as a swing bed arrangement 24 and operate as discussed abovebut instead of using a portion of the dehydrated feed stream 30 for theregenerative mode 28, a fresh regenerant stream 48 is introduced to theregenerative dehydration zone 12 and is used for regeneration of thespent Linde Type A molecular sieve. The fresh regenerant stream 48 ispreferably a light hydrocarbon stream (e.g. C₄-C₇ hydrocarbons) thatcontains little or no water (e.g. 1 wt. ppm or less).

The fresh regenerant stream 48 is passed through the heater 36 and isheated to a temperature of from about 200 to about 320° C. to form aheated regenerant stream 50. As illustrated, the heated regenerantstream 50 is introduced to the second dryer 22 that is in theregenerative mode 28 and is operating at the regenerative conditions.The heated regenerant stream 50 contacts the spent Linde Type Amolecular sieve and removes water to restore activity to the molecularsieve, forming regenerated Linde Type A molecular sieve and spentregenerant 52. The spent regenerant 52 is passed through a cooler 42where it is cooled to a temperature of about 60° C. or less andintroduced to a separation unit 44. The separation unit 44 separates thewater from the spent regenerant 52, forming a water waste stream 45 anda water-depleted regenerant stream 54 that may be recycled or removedfrom the regenerative dehydration zone 12.

Referring back to FIG. 1, the dehydrated feed stream 30 is removed fromthe regenerative dehydration zone 12 and is introduced to the guard bed14. The guard bed 14 contains sodium faujasite molecular sieve having asilica/alumina molar ratio of from about 2 to about 2.5, such as13×molecular sieve, which is described in The Atlas of Zeolite StructureTypes by W. M. Meier. In particular, 13×molecular sieve is a poroussynthetic crystalline zeolitic material having the followingcomposition:

1.0+/−0.2Na₂O:1.00Al₂O₃:2.5+/−0.5SiO₂

plus water of hydration. 13×molecular sieve has a cubic crystallinestructure that is characterized by a three-dimensional network withmutually connected intracrystalline voids accessible through poreopenings that will admit molecules with critical dimensions of up toabout 10 Å (e.g. 10 Å pore size). The sodium faujasite molecular sievewill permit the absorption of the larger contaminant molecules, such as,for example, oxygenates and sulfur compounds.

The guard bed 14 is operating at absorption conditions and thedehydrated feed stream 30 contacts the sodium faujasite molecular sieveto remove the contaminants and form a dehydrated contaminant-depletedfeed stream 56. In an exemplary embodiment, the absorption conditionsinclude a temperature of from about 0 to about 60° C., and a pressure soas to maintain a liquid phase, such as, for example, of from about 350to about 4,200 kPa. Preferably, the amount of contaminants present inthe dehydrated contaminant-depleted feed stream 56 is about 1 wt. ppm orless, and more preferably of about 0.5 wt. ppm or less, and mostpreferably of about 0.1 wt. ppm or less. In a specific example of thisembodiment, the amount of sulfolane present in the dehydratedcontaminant-depleted feed stream 56 is about 0.1 wt. ppm or less.

In an exemplary embodiment, a hydrogen feed stream 58 is passed througha third dryer 60 to remove water and is combined with the dehydratedcontaminant-depleted feed stream 56 to form a combined streams 62. Thecombined streams 62 is introduced to the paraffin isomerization zone 16that comprises an isomerization reactor 63. As illustrated, the combinedstream 62 is passed through a heat exchanger 64 to partially heat thecombined stream 62 to a temperature preferably of from about 65 to about175° C. to form a partially heated combined stream 66. The partiallyheated combined stream 66 is passed through a heater 68 and heated to atemperature preferably of from about 95 to about 205° C. to form aheated combined feed stream 70.

The heated combined feed stream 70 is introduced to the isomerizationreactor 63. In an exemplary embodiment, the isomerization reactor 63 isconfigured as a fixed-bed catalytic reactor operating at isomerizationconditions including a temperature of from about 95 to about 205° C. andcontains a high-activity chloride-promoted isomerization catalyst. Theheated combined feed stream 70 contacts the isomerization catalyst toform an isomerization effluent 72 that contains branched paraffins andthe like, such as, for example, isobutane, isopentane, and the like. Theisomerization effluent 72 is passed through the heat exchanger 64 and isremoved from the paraffin isomerization zone 16 for further processing,such as, for example, fractionation, separation, scrubbing, and thelike.

Accordingly, methods and apparatuses for treating ahydrocarbon-containing feed stream have been described. The variousembodiments comprise contacting a hydrocarbon-containing feed streamcomprising C₄, C₅, C₆, and/or C₇ hydrocarbons, water, and contaminantswith Linde Type A molecular sieve at dehydration conditions toselectively remove water from the feed stream to form a dehydrated feedstream and spent Linde Type A molecular sieve. The spent Linde Type Amolecular sieve is regenerated at regenerative conditions that include arelatively high temperature to help drive off the absorbed water andform a regenerated Linde Type A molecular sieve. Since the spent LindeType A molecular sieve is substantially free of the contaminants, agummy residue is preferably not formed on the molecular sieve fromexposure to the higher temperatures during regeneration. Therefore, theLinde Type A molecular sieve can be regenerated frequently as requiredrestoring its activity without forming a buildup of gummy residue thatmay otherwise cause premature permanent deactivation of the molecularsieve. The dehydrated feed stream is then contacted with sodiumfaujasite molecular sieve having a silica/alumina molar ratio of fromabout 2 to about 2.5 at absorption conditions to remove the contaminantsand form a dehydrated contaminant-depleted feed stream. Because thedehydrated feed stream is substantially free of water, the surface andpores of the sodium faujasite molecular sieve remain substantially freeof water, which has been found to prolong the activity of the molecularsieve. Preferably, the sodium faujasite molecular sieve is notregenerated and therefore, a gummy residue that may otherwise be formedfrom exposing the contaminants to higher temperatures duringregeneration is not produced.

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention. It being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims.

What is claimed is:
 1. An apparatus for treating ahydrocarbon-containing feed stream, the apparatus comprising: a firstdryer containing a first quantity of Linde Type A molecular sieve andconfigured to receive the hydrocarbon-containing feed stream comprisingC₄, C₅, C₆, and/or C₇ hydrocarbons, water, and contaminants and tooperate in a first dehydration mode at dehydration conditions effectiveto remove water and form a dehydrated feed stream and a first quantityof spent Linde Type A molecular sieve, wherein the contaminants compriseoxygenates, sulfur compounds, or combinations thereof; and a guard bedcontaining sodium faujasite molecular sieve having a silica/aluminamolar ratio of from about 2 to about 2.5 and configured to receive atleast a portion of the dehydrated feed stream and to operate atabsorption conditions effective to remove the contaminants and form adehydrated contaminant-depleted feed stream.
 2. The apparatus of claim1, further comprising a second dryer for containing a second quantity ofthe Linde Type A molecular sieve and configured to receive thehydrocarbon-containing feed stream and to operate in a seconddehydration mode at the dehydration conditions effective to remove waterand form the dehydrated feed stream and a second quantity of the spentLinde Type A molecular sieve, wherein the first and second dryers arecooperatively configured as a swing bed arrangement in which the firstdryer in the first dehydration mode receives the hydrocarbon-containingfeed stream to form the dehydrated feed stream while the second dryer ina first regenerative mode receives a first portion of the dehydratedfeed stream from the first dryer to regenerate the second quantity ofthe spent Linde Type A molecular sieve, and the second dryer in thesecond dehydration mode receives the hydrocarbon-containing feed streamto form the dehydrated feed stream while the first dryer in a secondregenerative mode receives a second portion of the dehydrated feedstream from the second dryer to regenerate the first quantity of thespent Linde Type A molecular sieve.
 3. The apparatus of claim 1, furthercomprising a second dryer for containing a second quantity of the LindeType A molecular sieve and configured to receive thehydrocarbon-containing feed stream and to operate in a seconddehydration mode at the dehydration conditions effective to remove waterand form the dehydrated feed stream and a second quantity of the spentLinde Type A molecular sieve, wherein the first and second dryers arecooperatively configured as a swing bed arrangement in which the firstdryer in the first dehydration mode receives the hydrocarbon-containingfeed stream to form the dehydrated feed stream while the second dryer ina first regenerative mode receives a first quantity of regenerant toregenerate the second quantity of the spent Linde Type A molecularsieve, and the second dryer in the second dehydration mode receives thehydrocarbon-containing feed stream to form the dehydrated feed streamwhile the first dryer in a second regenerative mode receives a secondquantity of the regenerant to regenerate the first quantity of the spentLinde Type A molecular sieve.
 4. The apparatus of claim 1, furthercomprising an isomerization reactor for containing an isomerizationcatalyst in the presence of hydrogen and configured to receive thedehydrated contaminant-depleted feed stream and to operate atisomerization conditions effective to form an isomerization effluentthat comprises branched paraffins, olefins, naphthenes, aromatics, orcombinations thereof.